getting ISO week
According to the definition in ?strptime (which is not the same as the ISO definition): format(x, "%W") returns "Week of the year as decimal number (00?53) using Monday as the first day of week (and typically with the first Monday of the year as day 1 of week 1). The UK convention." The first day of 2008 is a Tuesday which means that 2008 starts in week 0.
On Thu, Dec 11, 2008 at 2:31 PM, Hans W. Borchers <hwborchers at gmail.com> wrote:
Gabor Grothendieck <ggrothendieck <at> gmail.com> writes:
format(d, "%U") and format(d, "%W") give week numbers using different conventions. See ?strptime
Gabor,
the results of format(aDate, "W") appear to be incorrect anyway, see:
format(as.Date("2008-01-01"), "%W") #-> "00"
There is never a week 0, this should be week 1.
format(Sys.Date(), "%W") #-> "49"
but my business calendar says today's (Dec. 11, 2008) week is week 50
which is what Brian Ripleys proposed 'strftime(x, "%V")' returns.
There could be a format "%E" (not used up to now) for returning a
correct week number according to the European standard.
Yours, Hans Werner
On Thu, Dec 11, 2008 at 7:43 AM, Gustaf Rydevik <gustaf.rydevik <at> gmail.com> wrote:
Hi all, Is there a simple function already implemented for getting the ISO weeks of a Date object? I couldn't find one, and so wrote my own function to do it, but would appreciate a pointer to the "default" way. If a function is not yet implemented, could the code below be of interest to submit to CRAN? Best Regards, Gustaf --------------------
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